The invention relates to an apparatus for supply of combustion air to a combustion engine via an exhaust inlet to a turbocharger.
In engines in which it is a condition that the turbocharger provides increased power at low rotational speeds, we use a turbocharger with a pressure limiting valve, also known as a “waste gate valve”. This turbocharger is larger than actually required for the motor. The turbocharger is dimensioned with an overcapacity and will reach the desired charge pressure already at low rotational speeds. When the engine reaches the upper rotational speeds, the turbocharger provides too much air, and the overpressure becomes too high. The waste gate valve has an air hose which runs from the inlet manifold down to a diaphragm actuator which acts on the valve. When the charge pressure exceeds a predefined value the pressure against the diaphragm becomes so high that it opens the waste gate valve via a bar. The exhaust gas is then led past the turbo charger and out to the exhaust system, thus the pressure increase ceases. As soon as the admission regulator is reduced, the amount of exhaust against the turbine wheel in the turbo charger is reduced, and the air pressure in the inlet manifold is reduced. The waste gate valve will shut, and all the exhaust gas will again pass through the turbo charger.
It is important for a motor with a turbocharger to have an unobstructed air supply and as few obstacles as possible in the exhaust system. The turbo charger decelerates the exhaust gases and works to some degree as a silencer. The turbo charger and its connections to the exhaust system and the air inlet requires particularly good maintenance and inspection. In addition to lubricating the bearings in the turbo charger the oil has an important role to cool the bearing housing. The heat from the turbine housing propagates into the bearings and the lubricating oil. The oil is so strongly heated when the engine runs at high load that all turbo charged engines must be provided with an oil radiator. The engine should moreover have a lubricating oil which is adapted to motors with turbo chargers.